Vessels containing oil, such as storage tanks, tank cars, oceangoing tankers, barges, pipelines or other structures for storing or transporting crude oil or petroleum products will over a period of time accumulate large amounts of sludge made up of chemical or hydrocarbon deposits which deposits occur particularly in crude oils or heavy oils. Build up of such sludge over a period of time subtracts from the load carrying or storage capacity of the vessel. Further build up of sludge in oil conveying vessels such as tank cars or trucks results in carrying excess dead weight when the vessel is returned empty from a delivery point to a shipping point thus increasing cost of operations. Consequently the interiors of such vessels must be cleaned from time to time of accumulation of sludge.
Further vessels carrying or storing crude oil or other petroleum products, particularly barges and oceangoing tankers, are often used to carry other products besides oils or carry other grades of oils. It thus becomes necessary to cleanse the interior of such vessels prior to being loaded with other products or higher grades of oil Vessels of this type must be cleansed to a gas free state from time to time so that they may be entered for periodic inspection or for repair in the event of damage.
Existing techniques for cleaning oil carrying vessels has involved the use of steam and water applied in large volumes through spray nozzles against interior side walls of the vessels under high pressure. Occasionally chemicals are used in the cleaning but generally such cleaning systems involve the use of large volumes of water. This technique of cleaning has proved to be labor intensive, energy intensive, and generally results in the formation of large volumes of oil contaminated waste water. Vessels cleaned utilizing this technique are often not completely free of hydrocarbon deposits and are not suitable for upgrading and carrying or storing other products without further hand cleaning of the interior of the vessel.
It is therefore an object of our invention to provide for an apparatus and process for cleaning an oil contaminated vessel which will utilize a minimum of water and which will substantially completely clean an oil contaminated vessel of oil and any sludge in a comparatively short time and at minimal expense.
It is a still further object of the invention to provide for an apparatus and method of cleaning oil contaminated vessels of oil and sludge by which usable oil may be conveniently recovered for further use.